Leucocytes at a molecular level

Molecular biologists have left their imprint on almost every aspect of immunology investigation; one notable exception is the study of macrophage differentiation and activation. Few cells have as many interesting responses as the monocyte; and as most of the differentiation-activation responses occur without cellular proliferation, mononuclear phagocytes are excellent subjects in which to study environmental responses at the molecular level. Participants in a recent meeting(∗) considered how the techniques of molecular biology, often focused on problems of nerve-cell differentiation and fibroblast growth responses, could be used to address what many perceive to be the central question of macrophage biology: how are the many and diverse differentiation pathways regulated and can differentiation be described in distinct molecular terms from the state of activation?